Correction for MBH98 and MBH99 (27 September 2021) There appear to have been some minor errors in infilling some grid box temperatures series from the Jones & Briffa (1992) monthly data set in Mann et al (1998) and Mann et al (1999). We thank Hampus Soederqvist for bringing this to our attention. The correct surface temperature data were used in Caspar Ammann & Eugene Wahl?s reproduction of MBH98 and lead to very small differences in overall results. Their data and code can be found here: https://projects.ral.ucar.edu/rc4a/millennium/WA_supplement.html Last updated: DJB, 27 September 2021.